RIM has released another incremental operating system update for the PlayBook tablet, bumping the current version to 1.0.5 and adding a number of subtle-but welcome enhancements.

Several tweaks have been made to the upper-right corner of your PlayBook’s desktop, including a much-improved power widget. Tapping the battery icon now invokes a menu that allows users to adjust screen brightness and restart, shut down, or put the PlayBook into stand by mode. A slider has also been added which allows the brightness of the PlayBook’s display to be adjusted, and the OS will now alert users if an under-powered charging source is connected to the mini-USB port. Following the 1.0.5 update, the PlayBook can also charge itself while completely powered off.

Another key addition is the arrival of in-app payments, which will no doubt be a good fit for the numerous digital publications and games already available for the PlayBook. The real reason this matters, of course, is that some day very soon you’ll be able to purchase additional content for Angry Birds — it’s due to land in App World this summer. It’s also easier to connect to public Wi-Fi access points now — such as those at coffee shops and airports — thanks to the arrival of automatic hotspot detection. A handful of additional languages are now supported by the tablet OS as well, including Dutch, French, German, Italian, Spanish, and U.K. English.

It will be interesting to see whether the PlayBook OS 1.0.5 update takes care of the reduced battery life some users experienced following the previous update. As always, the update is available over-the-air, so tap through to your settings screen and then give the software updates button a poke. Now if they’d just hurry up and make with the Android app support, we’d be all set…